Pulmonary embolism is a blockage of the main artery (saddle emboli) of the lung or multiple bilateral branches by a substance that has travelled from elsewhere in the body through the bloodstream. The resulting obstruction of the blood flow through the lungs may cause increased pressure on the right ventricle of the heart that may lead to one or more of the following: dyspnea (shortness of breath), tachypnea (rapid breathing), chest pain of a “pleuritic” nature (worsened by breathing), and/or cough and hemoptysis (i.e., coughing up blood). The occurrence of this condition is about 1-2 per 1000 people per capita in the United States, and the likelihood of having a pulmonary embolism increases with age. After 80 years of age, a pulmonary embolism carries a 30% thirty day mortality using current standard of care of anticoagulation. Anticoagulant therapy is a common treatment for pulmonary embolisms. However, delivery of the treatment solution to the location in the pulmonary artery where the embolism is located may be clumsy and less than ideal. For example, current treatment methods include creating multiple holes in a unilateral femoral vein or multiple holes in bilateral femoral veins in order to obtain access in order to place multiple catheters in the right and left pulmonary arteries. Such methods may increase the risk of bleeding during and after treatment. Multiple access sites in a single femoral vein can increase the risk of hematoma. Further, when the systemic or catheter-directed anticoagulant is being actively administered in vivo, there is no way to know when the blockage has been completely removed thereby needlessly prolonging treatment in some cases. This extended treatment may further result in exposure of a patient to the lytic thereby increasing their risk of a devastating bleeding complication, such as cerebral hemorrhage.
Pulmonary hypertension is a type of high blood pressure that affects the arteries in the lungs and the right side of the heart. Pulmonary hypertension begins when pulmonary arteries and capillaries become narrowed, blocked, or destroyed. This makes it harder for blood to flow through the lungs, and raises pressure within the lungs' arteries. As the pressure builds, the right ventricle of the heart must work harder to pump blood through the lungs, eventually leading to right-side heart failure and hypoxia. Pulmonary hypertension is a serious illness that becomes progressively worse and is sometimes fatal. Signs and symptoms include shortness of breath, fatigue, dizziness or fainting, chest pressure or pain, swelling in the ankles, bluish color in the lips, and racing pulse or heart palpitations.
Right heart catheterization may be helpful for diagnosing pulmonary hypertension. During such a procedure, a catheter is placed into a vein in the patient's neck or groin. The catheter is then threaded into the patient's right ventricle and pulmonary artery. Right heart catheterization allows a medical professional to directly measure the pressure in the main pulmonary arteries and right ventricle. Such a procedure may also be used to monitor the effect medication may have on pulmonary hypertension of the patient. With a pressure sensing line in the pulmonary arteries, if the operator injects a drug and notes a decrease in pulmonary artery pressures, the medical professional may determine that that drug may be a good option for the particular patient.
There are a few medications that can be used to treat pulmonary hypertension with varying degrees of efficacy. Blood vessel dilators (vasodilators) open narrowed blood vessels. One of the most commonly prescribed vasodilators for pulmonary hypertension is epoprostenol (Flolan). A drawback is that the effect may only last a few minutes. This drug is continuously injected through an intravenous catheter via a small pump worn on the belt or shoulder. The patient may have to mix their own medications and may require frequent follow-up from a medical professional. A related drug, iloprost (Ventavis) can be inhaled every three hours through a nebulizer, a machine that vaporizes the medication. Inhalation of the drug may permit the drug to be delivered directly to the lungs. An alternative drug may include, endothelin receptor antagonists that may reverse the effects of endothelin, a substance in the walls of blood vessels that causes them to narrow. Another medication that may stop the narrowing of blood vessels is Ambrisentan (Letairis). Sildenafil (Viagra) and tadalafil (Cialis) may be used and work to open the blood vessels in the lungs. In addition, high-dose calcium channel blockers are drugs that may help relax the muscles in the walls of blood vessels. They include medications such as amlodipine (Norvasc), diltiazem (Cardizem, Tiazac), and nifedipine (Adalat, Procardia). Only a small number of patients suffering from pulmonary hypertension respond to calcium channel blockers. Diuretics can also be used. They are commonly known as water pills, and help eliminate excess fluid from the body. This may reduce the amount of work your heart has to do and may also help limit fluid buildup in the lungs.
Surgical options are limited for patients suffering from pulmonary hypertension. Atrial septostomy is an open-heart surgery that may be an option, but only for patients who do not respond to medication. In an atrial septostomy, a surgeon may create an opening between the left and right chambers of the heart to relieve pressure on the right side of the heart. Atrial septostomy may have serious complications including heart rhythm abnormalities (arrhythmias). Transplantation is another option in some cases for younger patients with idiopathic pulmonary hypertension. However, transplantation carries significant risks including rejection of the transplanted organ and serious infection, and the patient must take immunosuppressant drugs for the rest of their life to help reduce the chance of rejection.
Heart failure may occur when abnormal cardiac function causes failure of the heart to pump blood at a rate sufficient for metabolic requirements under normal filling pressure. Heart failure may be characterized clinically by breathlessness, effort intolerance, fluid retention, and poor survival. Heart failure may be caused by systolic or diastolic dysfunction. For example, left ventricular systolic dysfunction may be defined as left ventricular ejection fraction<0.40. Diastolic heart failure may be defined as a condition in which the heart does not fill with blood properly, and it may be difficult to diagnose. Directly monitoring pulmonary artery pressure via a procedure called right-heart catheterization is standard-of-care for hospitalized heart failure patients. However, in view of the chronic nature of heart failure, the patient may spend many days outside of the hospital, making at-home monitoring important. Systems have been developed for micro-electromechanical monitoring of pulmonary artery pressure as a means for early at home diagnosis of heart failure events, but they require the patient to visit their physician in the event of an episode in order to receive an injection of heart failure medication in order to prevent hospital admission.